Piezo-electric fuze assembly with bleed resistor



A. F. CARR 3,209,693

PIEZO-ELECTRIC FUZE ASSEMBLY WITH BLEED RESISTOR Oct. 5, 1965 Filed Feb.14, 1962 INVENTOR.

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ATTORNEY NQE United Sates Patent 3,209,693 PIEZO-ELECTRIC FUZE ASSEMBLYWITH BLEED RESISTOR Alton F. Carr, Woburn, Mass., assiguor, by mesneassignments, to Norris Thermador Corporation, Los Angeles,

Calif., a corporation of California Filed Feb. 14, 1962, Ser. No.173,243 3 Claims. (Cl. 102--70.2)

The present invention relates to nose caps for the war heads ofprojectiles.

While the invention is adapted for use wherever a war head is to explodein response to an electrical charge resulting from the crushing of apiezo-ceramic disc, it is herein described with particular reference torockets which well illustrate the problems involved.

In a rocket, the final assembly operation is the attachment of the nosecap and it is essential that the electrical conductors of the warhead beproperly connected to the piezo-ceramic disc, particularly when one is alead to the detonator and the other is grounded. It is also highlyimportant to provide the piezo-ceramic disc with a resistor to bleed offextraneous charges that may form thereon. In addition, the features justreferred to make for especial structural requirements both as tomanufacture and as to use.

The principal objective of the present invention is to enable the aboverequirements to be satisfied and, in accordance with it, a nose cap isprovided for use with a war head having a pair of contacts exposed inits forward end to which end the rearwardly opening cap portion of thenose cap is to be attached. A piezoceramic disc is in the front part ofthe cap portion and its faces are the positive and negative thereof withwhich positive and ground terminals, respectively, are in electricalcontact. A potting compound body, anchored in the cap portion, anchorsthe disc and terminals in place with the terminals protruding rearwardlyof the body for engagement with the contacts.

In the accompanying drawings, there is shown an illustrative embodimentof the invention from which these and other of its objectives, novelfeatures, and advantages will be readily apparent.

In the drawings:

FIGURE 1 is a side elevation of a rocket as illustrative of a projectilehaving a nose cap in accordance with the invention,

FIGURE 2 is a longitudinal section, on a substantially increased scale,through the nose cap,

FIGURE 3 is an exploded view of certain of the nose cap parts,

FIGURE 4 is a rear end view, on a further increased scale, of thepiezo-ceramic'body,

FIGURE 5 is a section taken approximately along the indicated lines 55of FIGURE 4,

FIGURE 6 is a longitudinal section, on a reduced scale, of the forwardend of a rocket war head with its nose cap attached thereto, and

FIGURE 7 is a section taken approximately along the indicated lines 7-7of FIGURE 6.

In FIGURE 1, a rocket is generally indicated at 10 and shown as having agenerally indicated head 11 which includes an ogive section 12 having acylindrical nose section 13, forwardly of a shoulder 14, and includingan inturned end wall 15 having a central opening 16, see FIGURES 6 and7, and a pair of spaced eccentric holes, 16A and 16B.

Attached to the front of the end wall 15, as by screws 17, is a body 18of insulation having a central hub 19 extending through the wall opening16 and provided with a forwardly flanged sleeve 20 which has a connector3,209,593 Patented Oct. 5, 1965 21 for the insulated lead 22 whichextends rearwardly through the hole-16A and through a metal, ground tube23, to the firing mechanism, which is not shown. The body 18 also has ametal sleeve 24 extending therethrough which receives the end of thetube 23. A sleeve 25 extends through the body 18 in registry with thehole 16B and it is connected to the sleeve 24 by a contact member 26.

The generally indicated nose cap 27, see FIGURES 2 and 3, consists of acap portion 28 which has, adjacent its rear, open end, a series ofcircumferentially spaced, inturned tabs 29 which resiliently engage thenose portion 13 of the ogive section 12 and an intermediate series ofcircumferentially spaced indentations 30.

Housed in the nose cap portion 28 is a disc-shaped, piezo-ceramic body31, see also FIGURES 4 and 5, whose rear face is its positive and itsfront face its negative provided with metal coats 31A and 31B, respectively. A metal disc 32 is secured to the face 31B by a conductiveadhesive. The body 31 has a marginal recess 33 to accommodate, withoutcontact therewith, the ground terminal 34 whose forward end 35 isdimensioned to enter the hole 36 in the disc 32. A slot 37 traverses thecenter of the body 31 and terminates in alined radial channels 37A and37B. The channel 37A is on the rear face of the body 31 while thechannel 37B is on the front face thereof. A resistor 38, anchored in theslot 37 as by potting compound 39, see FIGURE 2, has a lead 38A in thechannel 37A and a lead 38B in the channel 37B for the purpose ofinsuring the bleeding off of such extraneous charges as may develop onthe disc 32.

A positive terminal 40, see FIGURES 2 and 3, terminates in a flange 41which is cemented to the metal coat 31A on the body 31 and it and theterminal 34 protrude rearwardly beyond the body 42 of potting compoundwhich is anchored by the indentations 30 and which anchors the terminals34 and 40, the body 31 and the disc 32 in place. The terminals 34 and 40are dimensioned, see FIGURES 6 and 7, to extend into and preferablythrough the sleeves 25 and 20, respectively, of the insulation body 18thus to be electrically connected to the grounded conductor 23 and theinsulated lead 22.

I claim:

1. A nose cap for the war head of a projectile, the war head havingcircuitry including a pair of contacts exposed in its forward end, saidcap comprising a rearwardly opening cap portion for attachment to theforward end of the war head, a piezo-ceramic disc in the front part ofsaid cap portion, a metal disc secured to the front face of saidpiezo-ceramic disc and dimensioned to protrude marginally thereof, saidpiezo-ceramic disc having a central slot effecting communication betweenthe faces of said piezo-ceramic disc, each face having a groove openinginto said slot, a resistor within said slot including a pair of leads,each connected to a respective one of said faces and located in thegroove thereof, positive and ground terminals in electrical contact,respectively, with the rear face of said piezo-ceramic disc and theexposed margin of said metal disc, and a potting compound body anchoredin said cap portion and anchoring said discs and said terminals, thefree ends of said terminals protruding parallel with the cap axisrearwardly of said body, each for engagement with an appropriate one ofsaid contacts.

2. A nose cap for the war head of a projectile, the war head havingcircuitry including a pair of contacts exposed in its forward end, saidcap comprising a rearwardly opening cap portion for attachment to theforward end of the war head, a piezo-ceramic disc in the front part ofsaid cap portion, a metal disc secured to the front face of saidpiezo-ceramic disc and dimensioned to protrude marginally thereof, saidpiezo-ceramic disc having a central slot effecting communication betweenthe faces of said piezo-ceramic disc, a resistor in said slot andincluding a pair of leads, each connected to a respective one of saidfaces, positive and ground terminals in electrical contact,respectively, with the rear face of said piezo-ceramic disc and theexposed margin of said metal disc, and a potting compound body parallelto its axis anchored in said cap portion and anchoring said discs andsaid terminals, the free ends of said terminals protruding rearwardly ofsaid body, each for engagement with an appropriate one of said contacts.

3. A nose cap for the war head of a projectile, the war head havingcircuitry including a pair of contacts exposed in its forward end, saidcap comprising a rearwardly opening cap portion for attachment to theforward end of the war head, a piezo-ceramic disc in the front part ofsaid cap portion, a metal disc secured to the front face of saidpiezo-ceramic disc and dimensioned to protrude marginally thereof, saidpiezo-ceramic disc having a central slot effecting communication betweenthe faces of said piezo-ceramic disc, a resistor in said slot andincluding a pair of leads, each connected to a respective one of saidfaces, positive and ground terminals in electrical contact,respectively, with the rear face of said piezo-ceramic disc and theexposed margin of said metal disc, the positive terminal being axiallylocated with respect to said disc and including a flange dimensioned tostraddle said slot, and a potting compound body anchored in said capportion and anchoring said discs and said terminals, the free ends ofsaid terminals protruding rearwardly of said body parallel to its axis,each for engagement with an appropriate one of said contacts.

References Cited by the Examiner UNITED STATES PATENTS 5/34 Kielczewskil0228 2/59 RiZer et al. 1OZ70.2

1. A NOSE CAP FOR THE WAR HEAD OF A PROJECTILE, THE WAR HEAD HAVINGCIRCUITRY INCLUDING A PAIR OF CONTACTS EXPOSED IN ITS FORWARD END, SAIDCAP COMPRISING A REARWARDLY OPENING CAP PORTION FOR ATTACHMENT TO THEFORWARD END OF THE WAR HEAD, A PIEZO-CERAMIC DISC IN THE FRONT PART OFSAID CAP PORTION, A METAL DISC SECURED TO THE FRONT FACE OF SAIDPIEZO-CERAMIC DISC AND DIMENSIONED TO PROTRUDE MARGINALLY THEREOF, SAIDPIEZO-CERAMIC DISC HAVING A CENTRAL SLOT EFFECTING COMMUNICATION BETWEENTHE FACES OF SAID PIEZO-CERAMIC DISC, EACH FACE HAVING A GROOVE OPENINGINTO SAID SLOT, A RESISTOR WITHIN SAID SLOT INCLUDING A PAIR OF LEADS,EACH CONNECTED TO A RESPECTIVE ONE OF SAID FACES AND LOCATED IN THEGROOVE THEREOF, POSITIVE AND GROUND TERMINALS IN ELECTRICAL CONTACT,RESPECTIVELY, WITH THE REAR FACE OF SAID PIEZO-CERAMIC DISC AND THEEXPOSED MARGIN OF SAID METAL DISC, AND A POTTING COMPOUND BODY ANCHOREDIN SAID CAP PORTION AND ANCHORING SAID DISCS AND SAID TERMINALS, THEFREE ENDS OF SAID TERMINALS PROTRUDING PARALLEL WITH THE CAP AXISREARWARDLY OF SAID BODY, EACH FOR ENGAGEMENT WITH AN APPROPRIATE ONE OFSAID CONTACTS.